The researchers said they suspect that hand-washing dishes doesn’t get them as clean as the dishwasher does, which is actually a good thing because it can help protect against allergies by exposing family members to more bacteria.

Hand dishwashing is associated with other lifestyle factors that may also cause increased microbial exposure, Hesselmar told Live Science. For example, other studies have suggested that lower income levels, living in more crowded situations andimmigration statusare all linked with a reduced risk of allergies, and these three factors may also be associated with dishwashing practices. The researchers took these lifestyle factors into account in their analysis.

Although Hesselmar said the new findings were an “interesting observation,” he said it is too soon to recommend hand-washing dishes as an allergy-prevention strategy.

Early exposures

In previous studies, living on a farm during early life, having manyolder siblings, growing up in developing countries and being born by vaginal delivery have all been linked with fewer allergies in children. But in the new study, the researchers wanted to investigate the factors in people’s current daily lives that might have an impact on rising rates of childhood allergies. [9 Weirdest Allergies]

They analyzed data from more than1,000 children living in two regions of Sweden. Parents completed questionnaires asking whether their 7- and 8-year-old children had eczema, asthma or seasonal allergies. Parents also were asked about their typical dishwashing practices, as well as how frequently theirchildate fermented foods or farm-fresh foods, which have higher bacterial content than other foods.

Among thekidswhose parents hand-washed dishes,allergy rateswere even lower among the those who also ate more foods that were fermented or came directly from farms, according to the study.

These results held true even after the researchers took into accountparents’allergy histories, whether a child attended day care and whether they were around pets as an infant — three factors that can also influence a child’s risk of allergic diseases.

Two physicians at the University of California, San Francisco who wrote a commentary accompanying the study, said the results are interesting but that it’s too soon to put them into practical use.

They noted that one of the drawbacks of the findings is that, according to the hygiene hypothesis, early-life exposures to bacteria and germs would have the greatest effect on the immune system to prevent allergic conditions when they occur before 6 months of age. A six-month-old infant would have limited exposure to hand-washed dishes and utensils, especially if breast-fed.

The commentary concluded that more research is needed to understand how different lifestyle choices, such as dishwasher usage and microbial exposure in children, may influence allergic disease and prevention strategies.